• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Bollettino della Unione matematica italiana, B >Complex wavelet transform: an application to retrieve shear wave splitting time behavior at Mt. Vesuvius
【24h】

Complex wavelet transform: an application to retrieve shear wave splitting time behavior at Mt. Vesuvius

机译：复数小波变换：用于检索Mt处的剪切波分裂时间行为的应用程序。维苏威

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Shear wave splitting is the elastic equivalent of the well-known phenomenon of optical birefringence. A shear wave, propagating through an anisotropic volume, splits into two S waves (qS_1 and qS_2) that travel with different velocities and different polarization directions. This process generates two observables: Td that is the time delay between the two split S-waves, and the polarization direction of the faster one, qS_1. Interpretations indicate that in the upper crust this phenomenon occurs in zones of fluid-filled cracks, microcracks or preferentially oriented pore spaces. The time evolution of the anisotropic distribution of the microcracks due to differential stress according to the nonlinear anisotropic poroelasticity model, is explained by the migration of the fluid along pressure gradients between neighbouring microcracks and pores. In this framework, the shear wave splitting parameters are indicators of the state of stress in the upper crust. We obtained shear wave splitting measurements for local earthquakes occurring before the largest earthquake (M=3.6 occurred on October 9, 1999) recorded at Mt. Vesuvius after the last eruption (March 1944). The arrival times of split shear waves and the polarization directions were detected by using the wavelet transform of a three-component signal. In order to avoid any spatial effects on the time behaviour of the parameters, we performed the analysis for a selected data set of doublets. A short term (of the order of tens of days) variation of both Td and qSj parameters are retrieved before the occurrence of the M=3.6 event.
机译：剪切波分裂是弹性的等效光学双折射现象。传播通过各向异性体积的剪切波分裂成两个S波（qS_1和qS_2），它们以不同的速度和不同的偏振方向传播。这个过程产生两个可观察到的信号：Td是两个分开的S波之间的时间延迟，而更快的偏振方向是qS_1。解释表明，在上地壳中，这种现象发生在充满流体的裂缝，微裂缝或优先定向的孔隙空间区域。根据非线性各向异性多孔弹性模型，由微分应力引起的微裂纹各向异性分布随时间的演变，是通过流体沿相邻微裂纹和孔隙之间的压力梯度迁移来解释的。在这个框架中，剪切波分裂参数是上地壳应力状态的指标。我们获得了在Mt记录的最大地震（发生在1999年10月9日的M = 3.6）之前发生的局部地震的剪切波分裂测量。最后一次喷发后的维苏威火山（1944年3月）。通过使用三分量信号的小波变换来检测分裂剪切波的到达时间和偏振方向。为了避免对参数的时间行为产生任何空间影响，我们对选定的doublet数据集进行了分析。在M = 3.6事件发生之前，就可以检索到Td和qSj参数的短期（数十天量级）变化。

著录项

相似文献

  • 外文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号